Summary

ARNHEM, THE NETHERLANDS--
At a meeting of the European Society for Evolutionary Biology here in August, researchers described studies in viruses that point to a possible resolution of a dispute about the trajectory of evolution. One theory argues that evolution is like a staircase on which organisms evolve through a series of small genetic steps, while another postulates that genetic and environmental changes can derail the evolutionary process, picturing evolution as taking place on a landscape of numerous peaks and valleys where harmful mutations can displace an organism from a peak into a valley. The virus cultures described at the meeting suggested that both metaphors may be valid.